This invention relates to processing of high sulfur coal, and more particularly to a process of producing low sulfur distillates and low sulfur metallurgical type coke from a high sulfur coal.
Numerous processes are available for liquifaction of coal. These processes, exemplified by U.S. Pat. Nos. 3,966,585 and 3,997,422, typically include a digestion step in which particulate coal is partially dissolved in the presence of a hydrogen-rich solvent, followed by a filtration or other solids removal step, finally followed by a coking step. Additional related processes are described in U.S. Pat. Nos. 3,966,584; 3,617,513; 3,717,570; 3,726,785; 3,841,991; and 4,085,031. This type of process has been generally uneconomical heretofore because of the difficulties involved in removing finely divided solids from the dissolved coal and because of the severe process conditions required to effect significant sulfur removal.
Another approach is described in U.S. Pat. No. 3,960,701, which describes a process of reacting crushed coal in a hydrogenation reactor followed by removal of an oil-solids product stream which is subsequently coked in a delayed coker. Solids removal prior to coking is indicated to be unnecessary, but the coal dissolution step in that process is conducted under severe pressure and temperature conditions.
A coal liquefaction and coking process is described in my U.S. application Ser. No. 119,322, filed Feb. 7, 1980, now U.S. Pat. No. 4,292,165.
Coal treating processes using a hydrogen donor solvent also require a supply of hydrogen. Prior art processes typically required purchased hydrogen for this purpose.
There has been a long-standing need for a process which could treat a high sulfur coal to produce low sulfur liquid and solid products without the difficulties inherent in removing solids from the dissolved coal stream, without the need for purchased hydrogen, and without the necessity of a high temperature and pressure digestor as is required in the prior art. The process of this invention provides this capability.